Severing apparatus

ABSTRACT

Apparatus for severing material at selected locations comprises first and second dies. Each of the dies has sheet-severing elements in the form of narrow projections extending above the surface of the main body of the respective die. The sheetsevering elements define a layout of the selected material locations to be severed. At least one of the dies comprises a plurality of separate discrete die sections. An additional die section is provided as a replacement for each die section in the event of damage thereto.

United States Patent I [72] lnventor .l. Sarka {56] References Cited 7 g: Park ohm UNITED STATES PATENTS U] P 75 1,777,285 1930 Adsit 93/58.2 [22] F1led Sept. 12, 1968 2 682 208 1954 M onroe et al. 93/58.2X [45] named May 1971 3 383 991 1968 s 1 93 58 2 [73] Assignee Harris-lntertype Corporation 1 1 at a Cleveland, Ohio Primary Examiner-Andrew R. J uhasz Assistant Examiner-James F. Coan Attorney-Yount, Flynn and Tarolli ABSTRACT: Ap aratus for severing material at selected loca- [54] SEVEBING APPABATUS tions comprises f ll'Sl and second dies. Each of the dies has 13 Claims 7 Drawmg Figs sheet-severing elements in the form of narrow projections ex- [52] US. Cl 83/343, tending above the surface of the main body of the respective 83/665, 83/678, 83/698. 93158.2 die. The sheet-severing elements define a layout of the [51] Int. Cl B23d 25/12, selected material locations to be severed. At least one of the 826d 1/56 dies comprises a plurality of separate discrete die sections. An [50] Field of Search 83/343, additional die section is provided as a replacement for each die section in the event of damage thereto.

PATENTEB m 1 e um sum 2 BF 3 Q INVENTOR.

ALBERT J SAX/(A ATIURWEYJ mama] am am 3578.761

INVENTOR.

ALBEPTJ SAP/(A ATTORNEYS snvsrunc APPARATUS The present invention relates to an apparatus for severing material, and particularly relates to cooperable dies for use in severing material.

Recently developed dies which may be used for cutting and creasing sheet material are disclosed in Downie U.S. Pat. No. 3,142,233. The Downie patent discloses a pair of dies for cutting and creasing sheet material, and which dies have narrow lands which project above the main body of the die and form severing or creasing lands and which cooperate to effect severing or creasing of sheet material which is advanced between the dies. Other recently developed severing and creasing dies are disclosed in Sarka application Ser. No. 700,538. The dies disclosed in Ser. No. 700,538 also include projecting members which cooperate to effect the cutting and creasing of sheet material which is advanced between the dies.

In general, the dies disclosed in both the Downie patent and the Sarka application have projections which effect the severing of the material which is advanced between the dies. The projecting lands are formed on the dies in predetermined locations defining a layout of material locations which are to be severed. The layout primarily involves the arrangement of the projections so as to cut carton blanks, or a plurality of carton blanks from sheet material which is advanced between the dies.

In severing of the material, the dies are subjected to the possibility of damage. Such damage could result from material sticking to the dies or the fact that the die in a particular area has a large number of cutting lands or severing projections, which result in an excessive amount of loading in that particular area of the die. There are a variety of reasons why certain areas of the dies may wear and become damaged.

When one of the dies of a set of dies is damaged, this, of course, means that the die must be replaced in order to continue the cutting and creasing of the material. The replacement of the complete die is rather expensive. Moreover, the replacement of one die often necessitates the replacement of the cooperating die since cooperating dies are accurately made to work with each other.

Accordingly, the principal object of the present invention is the provision of an improvement in material-severing dies of the above noted type wherein a die which is damaged in a particular location may be repaired at a minimum cost and in a manner which does not involve the replacement of the entire die.

A further object of the present invention is the provision of a new and improved apparatus for severing materials in selected locations which includes cooperable material-severing dies and wherein at least one of the severing dies is formed of a plurality of separate discrete die sections which may be replaced in the event any one of them is damaged without replacing the other die sections.

A still further object of the present invention is the provision of a new and improved apparatus for severing material in selected locations and which includes cooperable materialsevering dies with one of the dies being formed of a plurality of die sections having projections thereon which comprise the sheet-severing elements and wherein an additional die section is provided which is similar in construction to the die sections which comprise the one die so that the additional die section may be used to replace any one of the die sections of the one die.

Another object of the present invention is the provision of a new and improved apparatus for severing materials in selected locations and which includes first and second relatively movable die support members and wherein first and second material-severing dies are supported on the first and second die support members and at least one of the dies comprises a plurality of die sections having projections thereon and wherein means is provided for securing each of the die sections to the die-support member and is releasable to provide for selective removal of at least one of the die sections from the die-support member while the other die sections remain secured thereto, for purposes of replacement of the one die section, in case of damage thereof, by another similar die sectionn Further objects and advantages of the present invention will be apparent to those skilled in the art to which is relates from the following detailed description of a preferred embodiment thereof, made with reference to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of an apparatus for severing sheet material and embodying the present invention;

FIG. 2 is a fragmentary sectional view showing the operative relationship between cooperating severing dies used in the apparatus of FIG. 1;

FIG. 3 is a plan view of a die used in the apparatus of FIG. 1 and formed of a plurality of die segments;

FIG. 4 is a view of an additional die segment which may be utilized for replacing any one of the die segments of the die of FIG. 3; and

FIGS. 5, 6 and 7 illustrate schematically the steps in the replacement of one of the die sections of FIG. 3 with the auxiliary die section of FIG. 4, in the event of damage to one of the die sections of FIG. 3.

The present invention provides an improved apparatus for severing material in selected locations and, in particular, provides improved material-severing dies which have narrow projections formed integrally with and extending from the main portion of the die for effecting severing of sheet material which is advanced between the dies. In particular, the construction of the dies may take many different forms and may be of the form disclosed in Downie U.S. Pat. No. 3,142,233, or may be of the form disclosed in Sarka application, Ser. No. 700,538, assigned to the assignee of the present invention. Moreover, dies of the present invention may be applied to a variety of types of severing apparatus and may be used in either rotary severing equipment, such as disclosed in Sarka U.S. Pat. No. 3,383,991 or in flat-bed or reciprocating severing equipment wherein one die is reciprocated toward and away from another die.

As representative of the preferred embodiment of the present invention, the present invention is illustrated in the drawings as applied to a rotary cutting and creasing apparatus 10 illustrated in FIG. I. The apparatus 10 includes a pair of die-support members, which in the illustrated embodiment comprises a pair of cylinders 11, 12 which cooperate to define a cutting nip 13 therebetween. Sheet material 14 in the form of cardboard, or the like, is advanced through the nip 13 formed by the rollers I1, 12 and is severed at selected locations as it is advanced through the nip.

The cylinder 11 carries a material forming or severing die 16, and the cylinder 12 carries a die 17. The dies l6, l7 cooperate to effect the cutting and creasing of the sheet material 14 which is advanced between the dies. The sheet material 14, of course, could be either in sheet form or in web form.

The dies I6, 17 which are provided on the cylinders 11, 12 and which cooperate to effect the cutting of the sheet material 14 which is advanced between the cylinders are herein disclosed as the type disclosed in the Downie U.S. Pat. No. 3,142,233. As illustrated in FIG. 2, the die 16 has a plurality of severing projections 20 thereon, and the die 17 has a plurality of severing projections 21 thereon. These projections are formed on the dies integrally with the main body 16a, 17a of the dies 16, 17 and project above the main bodies 16a, 17a of the dies 16, 17, respectively. The projections have flat land areas on the outer ends thereof which have a certain area of overlap, designated X in FIG. 2 when in the cutting nip 13, and cooperate due to this area of overlap to effect the formation of a cut line in the. sheet material. The dies 16, 17, as is known, also could be provided with a plurality of male and female creasing elements which would also be in the form of projections which extend from the main bodies 16a, 17a of the dies. As the material is advanced through the nip 13, the dies 16, 17 and specifically the projections 20, 21 effect a cutting of the material in the area of the overlap designated X in FIG.

2, and creasing of the sheet material can be effected by creasing elements on the dies 16, 17 and which are not shown.

The projections 20, 21, sever or cut the material 14 in selected locations. Specifically, the projections 20, 21 are located on the dies so as to define a layout of the selected material locations to be severed. A typical layout of the locations of severing elements or projections is illustrated schematically by the way of example in FIG. 3. The various full lines illustrate the location of the projections 20 on the die 16. Corresponding projection 21 would be formed on the die 17. It should be apparent from viewing FIG. 3 that the die 16 will cut carton blanks, the areas of which are designated 45- -54 in FIG. 3, from a single sheet of material 14 which is advanced through the cutting nip 13. The carton blanks are arranged five to a row, with two rows being formed from each rotation of the cylinders 11, 12. The layout shown is a layout in which the carton blanks are identical. The layout could be a mixed layout where the carton blanks differ.

The layout of the die 16, which is illustrated in FIG. 3, is such that when curved to form the die for the cylinders 11, 12, the die 16 would rotate in a direction indicated by the arrow in FIG. 3, and that would be the same direction that the sheet material 14 is advanced through the cutting nip. It should be apparent therefore that the leading edge of the die will be the edge 30, while the trailing edge of the die will be the edge 31. The side edges of the die are designated 32, 33.

In accordance with the present invention, at least one of the dies 16, 17 or both are made of a plurality of separate discrete sections. As disclosed herein, the die 16 is made up of a plurality of sections, generally designated 40, 41 and 42. Each of the die sections 40-42 is adapted to extend circumferentially around the cylinder 11 and when the die sections are placed in abutting side-by-side relationship, as illustrated in FIG. 3, the die sections form the complete die 16.

The die sections 40, 41, 42 each have a pattern or layout of sheet-severing elements 20 thereon, indicated by full lines in FIG. 3, and are designated 40a, 41a, and 42a, respectively. Moreover, the die sections 40-42 are similar in construction and have corresponding portions with similar positioning of the severing projections 20 thereon. As best illustrated in FIG. 3, the die section 40 has a portion which is designated A in FIG. 3 and a portion which is designated C. The portion A is the portion which effects cutting around areas 45, 46. The portion C effects cutting around half the areas 47, 48.

The die section 41 includes, what may be termed, three portions, designated A, B and C. The portion A cuts around the complete areas 49, 50, while the portion B cuts around the other half of the areas 47, 48. The portion A, of course, is identical to the portion A of the section 40. The portion C of section 41 is identical to the portion C of the section 40 and cuts around half of the areas 51, 52.

The die section 42 has portions which are designated A, B. The portion A cuts around the areas 53, 54 and is identical to the portions, designated A of the die section 40, 41. The portion B cuts around the other half of the areas 51, 52. The portion 8 is identical to the portion B of the die section 41. It should be apparent, of course, that with the die sections 40, 41, 42 positioned as shown in FIG. 3 with their side edges in abutting relationship, the complete die 16 is formed.

In view of the fact that the die sections 40, 41, 42 are separate discrete sections, these sections are preferably mounted independently by separate means on the cylinder 11 so that the sections can be separately mounted on the cylinder and separately removed from the cylinder 11. To this end, the cylinder 11 is provided with a plurality of leading and trailing edge clamps, indicated schematically in FIG. 3. The leading edge clamps, are located axially along the cylinder 111 and are designated 60a, 61a, 62a, and the trailing edge clamps are also located axially along the cylinder 11 and are designated 60b, 61b, 62b. The leading and trailing edge plate clamps are positioned in an axial gap 63 located in the cylinder 11, as is conventional.

The clamps 60a, 60b secure the die section 40 on the cylinder 11, and are releasable to permit the removal of the die section 40 from the cylinder 11 without removal of the die sections 41, 42. The clamps 61a, 611) secure the die section 41 to the cylinder 11, and the clamps 62a, 62b secure the die section 42 to the cylinder 11. The clamps 61a, 61b and 62a, 62b respectively, are releasable so that the die sections 41, 42 may be separately removed without removal of the other die sections. The clamps may be of any suitable construction, and reference may be made to US. Pat. No. 2,965,025 for a suitable clamping mechanism which may be utilized for separately clamping the die sections on the cylinder 11. In view of the fact that the details of the clamping mechanism which is utilized for holding the die sections 40-42 on the cylinder 11 do not form a part of the present invention, the clamps will not be described herein in detail.

In view of the similarity of the die sections 40, 41, 42, namely, that section 40 which includes portions A, C is identical with portions A, C of section 41 and that the die section 42 having the portions B, A is identical to the portions B, A of the section 41, the manufacture of the sections is simplified. Of course, these die sections are made in the manner described in the Downie patent referred to hereinabove. Specifically, the sections are made by etching process and the areas which are to form the projections both for severing and creasing are provided with a resist-hardened material through a photographic process. The other areas are then etched with a suitable etchant in order to etch away the main body of the die. As a result, the projections are formed on the die sections. In view of the fact that the sections are similar, the same negatives or similar negatives may be utilized in the photoetching process for manufacturing the die sections.

When the die plate 16 is mounted on the cylinder 11 and utilized for the severing of sheet material, the separate sections 40-42 of the die effect the severing of the material advanced through the nip 13 defined by the cylinders 11, 12. Certain severing projections, such as those designated 55, 56 on the die sections 40, 41 are aligned in an abutting relationship so that the adjacent ends of the projections 55, 56 are aligned. The fact that there may be a slight space, between the aligned ends of the projections 55, 56 does not affect the cutting of the material and the cutting is effected readily and without detrimental effects.

As the dies 16, 17 operate, there are many problems which could result in damage to one of the die sections 40-42 necessitating replacement of the particular die section. Of course, if the entire die is made as a one-piece unit, such as disclosed in the Downie patent or in the Sarka application referred to hereinabove, the entire die would have to be replaced at substantial cost. In accordance with the present invention an auxiliary or additional die section, designated 70, is provided and shown in FIG. 4, and may be utilized to replace any one of the sections 40, 41, 42 of the die 16 in the event that any one of these sections is damaged.

The additional or auxiliary die section 70, which is illustrated in FIG. 4, is identical to the die section 41, and similar reference numerals will be applied thereto to designate corresponding portions thereof. The additional die section 70 includes areas A, B, and C which are identical to the corresponding areas of section 41. It should be apparent, of course, that if the die section 41 becomes damaged all that is necessary to effect a replacement of the die section 41 with the die section 70 is to release the clamps 61a, 61b and remove the damaged die section 41 from the cylinder. The additional die section 70 can then be placed on the cylinder 11 and clamps 61a, 61b operated to secure the die section 70 thereon. Of course, during the replacement the die sections 40,42 are not removed from the cylinder 11 and remain in their respective positions.

In the event that the die section 40 would become damaged the additional die section 70 could also be used to replace the die section 40. In so doing, the area B of the die section 70 would have to be removed from the die section 70 by cutting along a line adjacent the area A and by suitably grinding down the undesired severing elements which would be projecting therefrom. With the area B removed and certain of the severing lands ground down, the additional section 70 would be identical to the section 40 and, therefore, could be used in place thereof. The section 70 could also be used for replacing the die section 42 in much the same manner as discussed above in connection with the section 70 replacing the die section 40. it would merely be necessary for the die section to replace the die section 42 to remove the area C of the die section 70, grind down the severing lands thereon which are unnecessary, and then to place the section 70 in position for the section 42. in this manner, the completed die would again be formed. In view of the above, it should be clear that the additional die section 70 can be used to replace any one of the die sections 40, 41, 42, and therefore, if any one of the sections is damaged the entire die need not be discarded and replaced at substantial cost.

It should be clear that certain of the cutting projections such as 56 on the die section 41, have a corresponding cutting projection on the die section 70, such as designated 56a. When the die section 70 is replaced for die section 41, the projection 56a, of course, must align with the projection 55 in order to provide a continuous cut line in the material. By having the adjacent ends of the projection 55, 56a aligned, they operate to provide a continuous cut line in the material. In this connection, as noted above, if there is some slight spacing between the aligned end of the cutting land 55 and the aligned end of the cutting land 56a on the additional die section 70, such spacing does not affect the severing action of these projections and a continuous cut line is still formed therein as long as the spacing between the aligned ends of the projections 55, 56a is not excessive.

FIGS. 57 illustrate schematically, the die sections 40, 41, 42 and the additional die section 70 and the steps which are performed in the replacement of one of the die sections, namely die section 42, by the die section 70. As illustrated in FIG. 5, the die 11 is completely formed by the die sections 40, 41, 42. The die section 70 is illustrated as being a replacement die section and may be stored in any suitable location for use in the event of damage to any one of the die sections 40, 41, 42.

For purposes of illustration, consider the die section 42 as having been damaged. The die section 42 is removed from the die-supporting member in the machine in which it is being used. in the preferred embodiment, the clamps 62a, 62b are released and the die section 42 is removed from cylinder 11. When the die section 42 is removed from cylinder 11, the die sections 40, 41 remain on the machine in their proper working location. In view of the fact that the section 42 is not exactly identical to the section 70, the section 70 must be modified in order to be made identical to the section 42. In this case, the area C of the section 70 must be removed from the section 70 in order to provide a die section which has the areas B, A and is identical to the die section 42. This, of course, is done by cutting the portion C of the die section 70 away from the sections B, A and then griding down those areas which remain which are unwanted or undesired severing or creasing lands. Once the portion of the section 70 is removed, the section 70, as indicated in FIG. 6, is identical to the section 42 prior to its being damaged. The section 70 may be placed on the die-supporting member in proper relationship with the sections 40, 41 in order to again provide a complete die having the desired layout of severing lands. The section 70 of course, as noted hereinabove, includes severing lands which must have their ends aligned with ends of the severing lands on the die section 41 so as to provide a continuous cut line in much the same manner as discussed hereinabove with respect to the severing lands 55, 56.

It should be apparent from the above that applicant has provided a new and improved apparatus for severing sheet material and that certain modifications, changes, and adaptations may be made therein and it is intended to cover all such changes, modifications, and adaptations which come within the scope of the appended claims.

Iclaim:

1. A die for severing sheet material into blanks comprising a plurality of plate members placed in side-by-side relationship to form said die, said die having opposed first sides and opposed second sides generally perpendicular to said opposed first sides and said plate members having first opposed sides providing said first sides of said die and abutting sides generally perpendicular to said first sides and portions extending along said first opposed sides of said plate members to be gripped to secure the plate members during a severing operation, adjacent ones of said plate members each having projection means thereon of substantially uniform height formed integrally with the plate member so as to be one piece therewith and adapted to sever said sheet material, said projection means on adjacent plate members comprising projection means extending transversely to the abutting sides of said plate members to fonn a continuation of the projection means on the adjacent plate member for severing sheet material to form a side of the blank which lies along a line generally transverse to the abutting side.

2. A die as defined in claim 1 wherein said plate members are flexible plate members and said projection means are formed by recesses in said plate members.

3. A die as defined in claim 1 wherein one of said plate members has projection means located along a line extending generally transversely of said first sides of said plate member for severing the entire extent of one side of a blank.

4. Apparatus for severing material in selected locations comprising first and second cooperable material severing dies, each of said first and second dies having sheet-severing elements in the form of narrow projections extending above the surface of the main body thereof, said sheet-severing elements being disposed on the respective dies to define a layout of the selected material locations to be severed, at least one of said dies comprising at least three separate discrete die sections, each of said die sections having projections thereon comprising the sheet-severing elements thereon, at least one projection on one die section having one end thereof aligned with an adjacent end of another projection on another die section, said projections having the aligned ends cooperating with at least one projection on the other of said dies to form a continuous cut line in the material, said apparatus further comprising an additional die section having projections corresponding in position to the projections on all of said die sections, two die sections of said three die sections being different from each other and said third die section having projections corresponding to all of the projections on said two die sections, said additional die section corresponding with said third one of said die sections so as to be replaceable for the third one of said die sections or for either of the said two die sections upon the removal of selected portions thereof in the event of damage to one of said two die sections.

5. A die as defined in claim 3 wherein said plate members are flexible and said projection means are formed by recesses in said plate member.

6. Apparatus for severing sheet material to form generally rectangular blanks having opposed first sides and opposed second sides extending generally perpendicularly to each other, said apparatus comprising a die-holding member, a die to be mounted onto said die-holding member, said die having portions along opposed first sides to be clamped to connect said die to the die-holding member during the severing operation, said die comprising a plurality of plate members having opposed first sides forming said first sides of said die and opposed second sides generally perpendicular to said first sides with adjacent plate members having ones of said second sides in abutting relationship with each other, die-holding means on said die-holding member for gripping said plate members, said plate members each having first projection means thereon integrally formed as one piece with the body of the plate member and located intermediate said second sides of the plate member and extending generally parallel thereto for severing along one of said second sides of a blank being severed with the projection means for severing the other opposed second side being on a different plate member and second projection means located at opposite ends of said first projection means and extending from said first projection means to at least one of said second sides of said plate member, said second projection means on adjacent die sections being aligned at their ends whereby said first opposed sides of said blank are formed by second projection means on different die sections.

7. Apparatus for severing sheet material as defined in claim 6 in which said die-holding member is a cylinder and said plate members are flexible plates.

8. Apparatus for severing material in selected locations comprising first and second relatively movable die-support members, first and second cooperable material-severing dies on said first and second die-support members, respectively, each of said first and second dies having sheet-severing elements in the form of narrow projections extending above the surface of the main body thereof, said sheet-severing elements being disposed on the respective dies to define a layout of the selected material locations to be severed, at least one of said dies comprising a plurality of separate discrete die sections, means for securing each of said die sections to one of said die support members and releasable to provide for selective removal of at least one of said die sections from said die-support member while the other die sections remain secured thereto, each of said die sections having projections thereon comprising the sheet-severing elements thereon, at least one projection on one of said die sections having one end thereof aligned with an adjacent end of another projection on another of said die sections when secured to said one die-support member, and said projections having the aligned ends cooperating with at least one projection on the other of said dies to form a continuous out line in the material, an additional die section having projections thereon corresponding in position to the projections on all of the die sections and being replaceable for any one of said plurality of die sections upon the removal of selected severing elements therefrom,

9. Apparatus for severing material in selected locations comprising first and second relatively movable' die-support members, first and second cooperable materiabsevering dies on said first and second die-support members, respectively, each of said first and second dies having sheet-severing elements in the form of narrow projections extending above the surface of the main body thereof, said sheet-severing elements being disposed on the respective dies to define a layout of the selected material locations to be severed, at least one of said dies comprising a plurality of separate discrete die sections, means for securing each of said die sections to one of said diesupport members and releasable to provide for selective removal of at least one of said die sections from said die-support member while the other die sections remain secured thereto, each of said die sections having projections thereon comprising the sheet-severing elements thereon, at least one projection on one die section having one end thereof aligned with an adjacent end of another projection on another die section when secured to said one die-support member, and said projections having the aligned ends cooperating with at least one projection on the other die to form a continuous cut line in the material, said first and second die support members being cylinders which define a severing nip and said means for securing each of said die sections to said die-support members comprising axially spaced clamps for securing the leading and trailing edges of the die sections independently to said cylinder for rotation therewith.

10. Apparatus for severing sheet material as defined in claim 7 wherein said means for gripping said plate members are disposed in a gap extending axially of said cylinder.

11. Die means for forming blanks comprising a die section for severing sheet material for forming a portion of a blank which is to be severed from the sheet material, the blank having first opposed sides and second opposed sides extending along lines generally perpendicular to said first opposed sides, said first and second opposed sides forming the outer periphery of the blank, said die section forming the outline of part of said blank for the full extent of the blank along one of said second opposed sides and comprising a plate member having first opposed sides and second opposed sides generally perpendicular to each other and defining the outer periphery of the plate member, said plate member having severing projections integrally formed with the body thereof so as to constitute a one-piece element for severing said sheet material along sides of said blank comprising first projection means located along a line intermediate said second opposed sides of the plate member and generally parallel thereto for severing along one of said second opposed sides of said blank for its full extent and second projection means located at the opposite ends of said first projection means for severing along said first opposed sides of said blank, said second projection means extending to one of said second opposed sides of said plate member to cooperate with projection means on an adjacent die section for severing the remainder of said first opposed sides of said blank, said die section having portions along its said first opposed sides to be clamped to secure the die during a severing operation.

12. A die section as defined in claim 11 wherein said plate member is of a substantially uniform thickness and said projection means is formed by recesses in said die member.

13. Die means as defined in claim 11 wherein said die means comprises a second die section having projection means thereon for forming the other of said second opposed sides of said blank and the remainder of said first opposed sides. 

1. A die for severing sheet material into blanks comprising a plurality of plate members placed in side-by-side relationship to form said die, said die having opposed first sides and opposed second sides generally perpendicular to said opposed first sides and said plate members having first opposed sides providing said first sides of said die and abutting sides generally perpendicular to said first sides and portions extending along said first opposed sides of said plate members to be gripped to secure the plate members during a severing operation, adjacent ones of said plate members each having projection means thereon of substantially uniform height formed integrally with the plate member so as to be one piece therewith and adapted to sever said sheet material, said projection means on adjacent plate members comprising projection means extending transversely to the abutting sides of said plate members to form a continuation of the projection means on the adjacent plate member for severing sheet material to form a side of the blank which lies along a line generally transverse to the abutting side.
 2. A die as defined in claim 1 wherein said plate members are flexible plate members and said projection means are formed by recesses in said plate members.
 3. A die as defined in claim 1 wherein one of said plate members has projection means located along a line extending generally transversely of said first sides of said plate member for severing the entire extent of one side of a blank.
 4. Apparatus for severing material in selected locations comprising first and second cooperable material severing dies, each of said first and second dies having sheet-severing elements in the form of narrow projections extending above the surface of the main body thereof, said sheet-severing elements being disposed on the respective dies to define a layout of the selected material locations to be severed, at least one of said dies comprising at least three separate discrete die sections, each of said die sections having projections thereon comprising the sheet-severing elements thereon, at least one projection on one die section having one end thereof aligned with an adjacent end of another projection on another die section, said projections having the aligned ends cooperating with at least one projection on the other of said dies to form a continuous cut line in the material, said apparatus further comprising an additional die section having projections corresponding in position to the projections on all of said die sections, two die sections of said three die sections being different from each other and said third die section having projections corresponding to all of the projections on said two die sections, said additional die section corresponding with said third one of said die sections so as to be replaceable for the third one of said die sections or for either of the said two die sections upon the removal of selected portions thereof in the event of damage to one of said two die sections.
 5. A die as defined in claim 3 wherein said plate members are flexible and said projection means are formed by recesses in said plate member.
 6. Apparatus for severing sheet material to form generally rectangular blanks having opposed first sides and opposed second sides extending generally perpendicularly to each other, said apparatus comprising a die-holding member, a die to be mounted onto said die-holding member, said die having portions along opposed first sides to be clamped to connect said die to the die-holding member during the severing operation, said die comprising a plurality of plate members having opposed first sides forming said first sides of said die and opposed second sides generally perpendicular to said first sides with adjacent plate members having ones of said second sides in abutting relationship with each other, die-holding means on said die-holding member for gripping said plate members, said plate members each having first projection means thereon integrally formed as one piece with the body of the plate member and located intermediate said second sides of the plate member and extending generally parallel thereto for severing along one of said second sides of a blank being severed with the projection means for severing the other opposed second side being on a different plate member and second projection means located at opposite ends of said first projection means and extending from said first projection means to at least one of said second sides of said plate member, said second projection means on adjacent die sections being aligned at their ends whereby said first opposed sides of said blank are formed by second projection means on different die sections.
 7. Apparatus for severing sheet material as defined in claim 6 in which said die-holding member is a cylinder and said plate members are flexible plates.
 8. Apparatus for severing material in selected locations comprising first and second relatively movable die-support members, first and second cooperable material-severing dies on said first and second die-support members, respectively, each of said first and second dies having Sheet-severing elements in the form of narrow projections extending above the surface of the main body thereof, said sheet-severing elements being disposed on the respective dies to define a layout of the selected material locations to be severed, at least one of said dies comprising a plurality of separate discrete die sections, means for securing each of said die sections to one of said die support members and releasable to provide for selective removal of at least one of said die sections from said die-support member while the other die sections remain secured thereto, each of said die sections having projections thereon comprising the sheet-severing elements thereon, at least one projection on one of said die sections having one end thereof aligned with an adjacent end of another projection on another of said die sections when secured to said one die-support member, and said projections having the aligned ends cooperating with at least one projection on the other of said dies to form a continuous cut line in the material, an additional die section having projections thereon corresponding in position to the projections on all of the die sections and being replaceable for any one of said plurality of die sections upon the removal of selected severing elements therefrom.
 9. Apparatus for severing material in selected locations comprising first and second relatively movable die-support members, first and second cooperable material-severing dies on said first and second die-support members, respectively, each of said first and second dies having sheet-severing elements in the form of narrow projections extending above the surface of the main body thereof, said sheet-severing elements being disposed on the respective dies to define a layout of the selected material locations to be severed, at least one of said dies comprising a plurality of separate discrete die sections, means for securing each of said die sections to one of said die-support members and releasable to provide for selective removal of at least one of said die sections from said die-support member while the other die sections remain secured thereto, each of said die sections having projections thereon comprising the sheet-severing elements thereon, at least one projection on one die section having one end thereof aligned with an adjacent end of another projection on another die section when secured to said one die-support member, and said projections having the aligned ends cooperating with at least one projection on the other die to form a continuous cut line in the material, said first and second die support members being cylinders which define a severing nip and said means for securing each of said die sections to said die-support members comprising axially spaced clamps for securing the leading and trailing edges of the die sections independently to said cylinder for rotation therewith.
 10. Apparatus for severing sheet material as defined in claim 7 wherein said means for gripping said plate members are disposed in a gap extending axially of said cylinder.
 11. Die means for forming blanks comprising a die section for severing sheet material for forming a portion of a blank which is to be severed from the sheet material, the blank having first opposed sides and second opposed sides extending along lines generally perpendicular to said first opposed sides, said first and second opposed sides forming the outer periphery of the blank, said die section forming the outline of part of said blank for the full extent of the blank along one of said second opposed sides and comprising a plate member having first opposed sides and second opposed sides generally perpendicular to each other and defining the outer periphery of the plate member, said plate member having severing projections integrally formed with the body thereof so as to constitute a one-piece element for severing said sheet material along sides of said blank comprising first projection means located along a line intermediate said second opposed sIdes of the plate member and generally parallel thereto for severing along one of said second opposed sides of said blank for its full extent and second projection means located at the opposite ends of said first projection means for severing along said first opposed sides of said blank, said second projection means extending to one of said second opposed sides of said plate member to cooperate with projection means on an adjacent die section for severing the remainder of said first opposed sides of said blank, said die section having portions along its said first opposed sides to be clamped to secure the die during a severing operation.
 12. A die section as defined in claim 11 wherein said plate member is of a substantially uniform thickness and said projection means is formed by recesses in said die member.
 13. Die means as defined in claim 11 wherein said die means comprises a second die section having projection means thereon for forming the other of said second opposed sides of said blank and the remainder of said first opposed sides. 